浑善达克沙地作为中国北方沙漠化最严重的地区之一,已被列入全国重点生态环境建设地区,其沙漠化发展过程及其影响因素研究具有重要意义。利用1985—2017年浑善达克沙地5期遥感影像数据,通过eCognition 9.0 软件,采用面向对象计算机自动分类法,获取沙漠化指数,进行浑善达克沙地沙漠化时空演变特征研究,并利用主成分分析法,进行了沙漠化驱动机制研究。结果表明：近30 a,浑善达克沙地沙漠化土地面积以2002年为转折点呈现先增加后减少的趋势,其中轻度沙漠化土地面积先减少后增加,由42.1%减少到20.9%后又增加到32.1%,主要分布于东部地区;中度沙漠化有逐渐增加的趋势,由20.6%增加到39.0%,分布于中部地区;重度沙漠化土地由30.3%减少到22.6%,而极度沙漠化先增加后减少,由7.0%增加到16.0%后又减少到6.3%,分布于西部及以南逐渐往西北方向移动。沙漠化程度空间上形成由西向东逐渐减轻的趋势。浑善达克沙地沙漠化发展过程受年末总人口、国内生产总值、三次产业、载畜量、耕地面积等人为因素影响较大,自然因素起到辅助作用。因此,沙漠化治理过程中,有效实施退耕还林还草和禁牧、休牧等政策,合理开展治沙防沙工程,进一步改善浑善达克沙地沙漠化,推动区域生态环境的健康发展。

The Hunshandake Sandy Land, as one of the most serious desertification areas in northern China, has been listed as a national key ecological environment construction area. A series of policies to control sand dust sources and restore the ecological environment in the Hunshandake Sandy Land has been implemented, such as returning farmland to forest and grassland and forbidding and restricting grazing, so as to curb the development momentum of desertification and improve the regional ecological environment. However, the ecological environment of the Hunshandake Sandy Land is fragile and, coupled with significant climate change, unreasonable land use patterns, excessive reclamation, grazing, and other phenomena, has not completely improved, resulting in the ecological environment of the area still facing problems. Therefore, it is of great significance to study the process of desertification and its influencing factors. The desertification index was calculated and the spatial-temporal evolution characteristics of desertification were studied in five remote sensing imagery periods of the Hunshandake Sandy Land from 1985 to 2017 using eCognition 9.0 and an object-oriented computer automatic classification method; further, the driving mechanism of desertification was studied using principal component analysis. In this paper, the research period of the Hunshandake Sandy Land desertification has been extended, the data have been updated (desertification data for 2017 were added), and the driving mechanism research has been synchronized with the desertification cycle. The results show that the desertification land area of the Hunshandake Sandy Land increased and then decreased over the last 30 years, with a turning point in 2002. The area of mild desertification first decreased and then increased (from 42.1% to 20.9% and then to 32.1%), mainly in the east. Moderate desertification tended to increase gradually (from 20.6% to 39.0%) and is distributed in the central region. However, severe desertification decreased from 30.3% to 22.6%. Extreme desertification first increased and then decreased, increasing from 7.0% to 16.0% and then decreasing to 6.3%, and is distributed in the west and southwest and has gradually moved to the northwest. Overall, the spatial distribution of the desertification degree decreases from west to east. The development process of desertification in the Hunshandake Sandy Land has been greatly influenced by human factors, while natural factors play an auxiliary role. Of the human factors, the contribution rate of total population, GDP, and three industries to the principal component is higher than 0.9, while the contribution rates of the livestock carrying capacity and cultivated land area have reached 0.694 and 0.803, respectively, having a significant impact on desertification. Increasing precipitation and decreasing wind speed can alleviate desertification to some extent. The contribution rates of precipitation and the annual maximum wind speed to the principal component are 0.851 and 0.957, respectively. The land contract responsibility system implemented in 1980 and a series of ecological and environmental protection policies implemented by the state after 2000 play a key role in the Hunshandake Sandy Land switching from growth to mitigation. Therefore, in the process of desertification control, we need to implement policies of returning farmland to forest and grass and grazing prohibition and restriction to decrease the desertification of the Hunshandake Sandy Land and to promote the healthy development of the regional ecological environment.